Has effects on the tubules of the testes to form sperm
Has effects on Leydig cells which form testosterone & nourish the sperm.
Which tests do you order to diagnose male hypogonadism?
TOTAL and BIOAVAILABLE (bound - not as accurate), free if necessary. (I think) Also get an LH level, FSH level and prolactin (elavated prolactin performs negative feedback on GnRH)
Primary hypogonadism lab values
- Low testosterone
- High-normal to High LH and FSH
- (Problem is with testes not producing)
Secondary hypogonadism lab values
- Low testosterone
- Normal to low LH and FSH
- (problem is in the pituitary or hypothalamus)
Primary hypogonadism causes
- Klinefelter's syndrome & other (mostly congenital) issues
- Drugs, radiation, mumps, chronic disease (HIV, etc.)
Male hypogonadism that results in deficient secondary sex-characteristics (high-pitched voice, lack of hair growth, arm span > high by 5 cm and long legs with shorter torso.
- Male with extra X-chromosome
- Low amounts of inhibin are produced in testes so it doesn't feed back appropriately & leads to increased levels of LH and FSH with low testosterone & high estradiol
- Tall, breast development, small testes, slightly feminized physique w/ mildly impaired IQ.
- Diagnose with buccal smear-looking for barr bodies
- No trx. listed - testosterone after puberty?
Secondary hypogonadism causes
- Kallman's syndrome (lack of smell)
- Idiopathic hypogonadotropic hypogonadism w/ retardation
- Abnormal beta-subunit of LH or FSH
- Sarcoidosis, drugs, alcohol, etc.
Tests for hypogonadism
- Serum testosterone - 8:00 am
- Serum FSH & LH w/ prolactin
- Peripheral leukocyte karyotype (Klinefelter's)
- Testosterone replacement (not for people w/ potential reversibility because you can suppress their ability to make their own testosterone)
- Treat underlying disease
Measuring injectable steroids
Measure midway between injections
Measure gel steroid levels
After one month
Measure oral steroids
After administering 3-5 hours
Rise with androgen therapy but should remain within the reference range. Maximal increase in prostate volume occurs 3 mos after initiation of trx.
Seen most commonly with injectable steroids
Alkylated oral testosterone can cause this. Measure LFTs when administering oral therapy
Should see within 3-6 months
Can be caused by low testosterone but is more likely due to another problem. Can give a phosphodiesterase inhibitor (Viagra) for that.
- For secondary hypogonadism only
- GnRH pulsatile infusion
- hCG- stimulates the Leydig cells to produce testosterone (necessary for sperm production)
- hMG - stimulates the seminiferous tubules to produce sperm